let  shopArray = [
    {pcode:3,pname:"面包",price:4,num:3},
    {pcode:2,pname:"火腿",price:6,num:1},
    {pcode:4,pname:"三明治",price:10,num:2},
    {pcode:8,pname:"牛排",price:25,num:4}
];